The subject invention is directed toward the art of tube fittings and couplings and, more particularly, to an improved coupling nut assembly.
The invention is particularly useful for allowing female coupling nuts to be installed on integral glands carried on flow system devices, such as valves.
One commonly used tube fitting for vacuum and high purity gas systems is a face seal arrangement using cylindrical gland elements having end flanges and sealing end faces. The gland elements are driven toward one another by cooperating, threadedly connected male and female nut members that engage the gland elements behind the end flanges. A fitting of the general type under consideration is shown in commonly assigned U.S. Pat. Nos. 3,521,910; 4,552,389; 4,650,227; and 5,145,219.
In certain situations, it is highly desirable to have the gland elements effectively constitute an integral part of a flow system device, such as a valve. In such instances, one of the two cooperating nut members must be captured on the gland element formed on the flow system device. That is, the nut member, normally the female nut member, must be located between the end flange on the gland and the body of the flow system device. In the past, this has been achieved by locating the female nut on a small separate gland element and then welding the gland element to the flow system device. Alternatively, the female nuts have been provided with various connectors, such as slide wires, to allow them to be moved over the end flanges on the gland element and connected thereto after formation of the gland element on the flow system device (see, for example, U.S. Pat. Nos. 5,152,499 and 2,310,490).
Each of the above-discussed methods of forming an integral gland member and attaching an associated female nut on a flow system device has certain disadvantages. For example, both of the methods result in present manufacturing problems. In addition, with some of the connector systems, the space requirements are excessive.